【2018.06.19学习笔记】【linux高级知识 13.1-13.3】

13.1 设置更改root密码

先启动mysql：

[root@nginx ~]# /etc/init.d/mysqld start
Starting MySQL. SUCCESS! 
[root@nginx ~]# ps aux |grep mysql
root       1407  0.4  0.0 113308  1624 pts/0    S    20:27   0:00 /bin/sh /usr/local/mysql//bin/mysqld_safe --datadir=/data/mysql/ --pid-file=/data/mysql//nginx.pid
mysql      1515  5.5 24.1 1300824 451192 pts/0  Sl   20:27   0:00 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/data/mysql --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=/data/mysql/nginx.err --pid-file=/data/mysql//nginx.pid
root       1539  0.0  0.0 112720   972 pts/0    R+   20:27   0:00 grep --color=auto mysql

登陆mysql：

mysql -uroot  //以用户root登陆
[root@nginx ~]# mysql -uroot
-bash: mysql: 未找到命令

若是此时提示：mysql，无此命令，是由于没有把/usr/local/mysql/bin/mysql 加入PATH环境变量中

能够临时加入：mysql就生效了

[root@nginx ~]# export PATH=$PATH:/usr/local/mysql/bin/
[root@nginx ~]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.6.36 MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

要永久生效，就要在/etc/profile 下加入

[root@nginx ~]# vim /etc/profile
##省略内容
unset -f pathmunge
export PATH=$PATH:/usr/local/mysql/bin/mysql
[root@nginx ~]# source /etc/profile  //使配置生效

或者用别名：

alias mysql='/usr/local/mysql/bin/mysql'

指定用户和密码登陆：

[root@nginx ~]# mysql -uroot -p  //回车，而后输入密码便可登陆，无密码直接按回车。
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.6.36 MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

若是root没有密码，能够设置密码：

[root@nginx ~]# mysqladmin -uroot password '7826078'  //在单引号内设置密码，按回车
Warning: Using a password on the command line interface can be insecure.
[root@nginx ~]# mysql -uroot -p7826078  //登陆验证
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 5.6.36 MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

修改密码：

[root@nginx ~]# mysqladmin -uroot -p'7826078' password '961303'  //按回车修改生效
Warning: Using a password on the command line interface can be insecure.
[root@nginx ~]# mysql -uroot -p961303
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.6.36 MySQL Community Server (GPL)

Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

若是密码忘记了，能够重置密码：

[root@nginx ~]# vim /etc/my.cnf  //在配置文件的[mysqld]下增长

# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html
# *** DO NOT EDIT THIS FILE. It's a template which will be copied to the
# *** default location during install, and will be replaced if you
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html
# *** DO NOT EDIT THIS FILE. It's a template which will be copied to the
# *** default location during install, and will be replaced if you
# *** upgrade to a newer version of MySQL.

[mysqld]
skip-grant   //忽略受权
[root@nginx ~]# /etc/init.d/mysqld restart  //重启一下mysql服务。
Shutting down MySQL.. SUCCESS! 
Starting MySQL. SUCCESS! 
[root@nginx ~]# mysql -uroot   //而后再登陆就不用密码了
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.6.36 MySQL Community Server (GPL)

mysql> use mysql  //切换到mysql库，修改mysql库下的user表
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed

mysql> select password from user where user='root';  //查询root用户的密码字段，密码是加密显示的，是password函数生成的
+-------------------------------------------+
| password                                  |
+-------------------------------------------+
| *3169EA1E35BFDB495D332C42C34EBB9E797543DD |
|                                           |
|                                           |
|                                           |
+-------------------------------------------+
4 rows in set (0.00 sec)

mysql> update user set password=password('7826078') where user='root'; //在user表里更新root用户的密码
Query OK, 4 rows affected (0.01 sec)
Rows matched: 4  Changed: 4  Warnings: 0

[root@nginx ~]# vim /etc/my.cnf //在配置文件的[mysqld]下，删除这行 skip grant
[root@nginx ~]# /etc/init.d/mysqld restart //重启一下mysql服务。而后就能够用新密码登陆了
Shutting down MySQL.. SUCCESS! 
Starting MySQL. SUCCESS! 

[root@nginx ~]# mysql -uroot -p7826078  //用新密码登陆成功
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.6.36 MySQL Community Server (GPL)

13.2 链接mysql

链接本机的mysql: tcpip协议通讯

mysql -uroot -p密码  //直接输入用户名和密码，默认就是链接本机的mysql

链接远程的mysql： tcpip协议通讯

mysql -uroot -p密码 -h127.0.0.1 -P3306 //-h指定远程ip，-P指定远程端口

若是本机安装了多个mysql，能够指定socket链接mysql： socket协议通讯

mysql -uroot -p密码 -S/tmp/mysql.sock //也是链接本机的mysql

在shell中经常使用的，链接mysql后，执行一些命令：

mysql -uroot -p密码 -e "show databases"

13.3 mysql经常使用命令

查询库：

show databases;

切换到指定库：

use mysql; //mysql是指定的库名

查看表：

show tables;

查看表的字段：

desc 表名;

查看表是怎么建立的：

show creat table 表名\G; //G 纵向显示

查看当前登陆用户：

select user();

查看当前使用的库：

select database();

建立库：

creat databases db1; // db1为库名

建立表：

creat table 表名('字段1' 类型，'字段2' 类型);
craet table t1('id' int(4),'name' char(40)) ENGINE=InnoDB DEFAULT CHARSET=utf8;

查看数据库版本：

select version();

查看状态：

show status;

查看各参数：

show variables;

查看具体参数：

show variables like 'max_connect%';  //%是通配符

修改参数：

set global max_connect_errors=1000; //在内存中生效，要永久生效，该my.cnf文件

查看队列：

show processlist; //查看进程信息，mysql在作什么操做

查看完整队列信息：

show full processlist; //完整的进程信息，什么用户链接、执行什么操做、有无锁表等。